Can I use a apex:repeat on a VF page to iterate through related external data?

Hi Piyush, Yes you can use apex:repeat in a vf page.

You should be able to use the external objects just like a custom object. Here is an example using the repeat tag on the sample external object from the trailhead project:

<apex:page standardController="Account">
<apex:detail relatedList="false"/>
<apex:repeat value="{!Account.Orders__r}" var="order">
<apex:outputField value="{!order.orderID__c}"/>
</apex:repeat>
</apex:page>

Hope this helps you.